Process of manufacturing pulp for paper production



Patented Aug. 7, 1928. UNITED STATES PATENT OFFICE.

DINSHAW RATTONJI NANJI, F IBIRCEFIELDS, BIRMINGHAM, ENGLAND.

PROCESS OF MANUFACTURING PULP FOR PAPER PRODUCTION.

No Drawing. Application filed November 5, 1926, Serial No. 146,575, and inGreat Britain August 17, 1926.

This invention relates to a new or imsolution of low concentration and at high proved process for the treatment of plant, pressure. The preliminary depectinizing woody and other cellulosic materials for the treatment avoids possibility of staining or production of pulp in paper manufacture colouring the substances on addition of the 60 and for other purposes. alkali.

Hitherto the pulp has been obtained'from Following the delignification the pulp is the woody or like tissue, mainly by either bleached and dried according to the ordinary one of two processes, viz :that known as methods of paper production. the sulphite process and that making use of The alkali used also may be recovered by 65 caustic alkali. The pulp obtained by the concentration electrolytically or in any other first process is not pure chemically and convenient manner. though it may be cheaply produced, tech- If desired, instead of treating the woody nical difliculties are encountered, the t-reator like raw material with the improved proment is lengthly, the time ranging from 6 cess, I may treat impure celluloses obtained 70 to hours, and serious corrosion of the by other methods such for example as sulplant occurs owing to sulphurous fumes. In phite pulp, soda pulp or the like, to obtain the second process making use of caustic a product pure enough for preparing cellusoda, it has not been found possible hitherto lose derivatives. to delignify the tissue satisfactorily with a As an example of the improved process as 20 solution of alkaliof lower concentration than applied to bagasse from sugar cane, the 68%. The use of an alkali liquor of such fibres are first disintegrated into lengths of a concentration considerably increases the from A to 1. This is done by the crushexpense of the process and even so the time ing rollers employed in the sugar expression of treatment cannot be allowed to fall below process. 1000 lbs. of this mass is then 25 from 4 to 6 hours. Up to the present efforts tritul'ated With 300 gallons preferably of to use high temperatures accompanied by a nearly boiling solution of 4% caustic use of concentrated solutions have resulted alkali. lVhen the whole of the soda soluin very considerable wastage due to alkaline tion is well mixed with the mass, this is hydrolysis of the cellulose to soluble prodthen transferred to a suitable digester and 30 ucts thus giving a lower yield and a mod heated say by steam under pressure, or by uct difiicult to bleach. According to the superheated steam until the temperature of present invention, the Woody or like raw the mixture reaches 185 C. It is mainmaterial is treated for a short period, viz: taincd at this temperature for approxifrom half to one hour with alkaline solution mately one hour and the digested "mass is no of concentration up to 4% and the mixture then pressed out in a suitable press to reheated either under high pressures, approxmove the caustic lye, Washed with hot Water, imating to 10 atmospheres, or at temperaand bleached in any suitable manner. tures corresponding to these pressures. By Where considerable quantities of pectin this improved process making use of relaand sugars are present in the raw material, 05 40 tively low concentration and working at it is preferable to employ as a depectinizing high temperatures for a short time, it is agent, a 0.5% solution of ammonium sulpossible to delignify the raw material in phate or other neutral salt of ammonium a very effective manner. or of an alkali metal in quantities suflicient Under these conditions, it is possible to to immerse the material under treatment. delignify all the cellulosic materials without I claim any serious loss of the cellulose which more- 1. A process of manufacturing pulp by over is obtained ina readily bleachable treatment of suitable cellulosic materials condition. I with an alkali solution of concentration up The invention also includes the treatment to 4% and the mixture heated to a tempera- 1 50 of raw materials containing pectin and ture corresponding to a vapour pressure of sugars, in which case the cellulosic material from 7 to 10 atmospheres and preferably is first acted" upon .with aipectin solvent, as near 10 atmospheres as possible for a such as a dilute solution of a neutral salt of period of from one half to one hour. one of the alkali metals or of ammonia; 2. A process of manufacturing pulp by after this preliminary'treatment the material the treatment of bagasse from sugar cane, is submitted to the action of the caustic whereby the fibres of the raw material havcellulosic materials containin pectin and sugars are submitted to a preliminary treatment with a pectin solvent such as a dilute solution of a neutral salt of one of the alkali metals or of ammonium, and subsequently to treatment with an alkali solution of concentration up to 4% and the mixture heated to a temperature corresponding to a vapour pressure of from 7 to 10 atmospheres and preferably as near 10 atmospheres as possible for a period of from one half to 25 one hour.

In testimon whereof I aflix my signature.

DINS W RATTONJI NANJI. 

